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J Tiers
09-18-2010, 09:48 PM
Since we seem to be discussing matters of electrical nature recently..... here is a tester for the understanding of one type of component...... a transformer.

OK

Suppose you have a transformer with a single primary winding and a single secondary winding, each consisting of many turns of wire. Current in the primary produces a "magnetic flux" in the core, and the changing flux in the core induces a voltage in the secondary.... In fact, current in ANY winding produces a magnetic flux in the core.

The "magnetic flux" in the core is created by current in the primary..... which draws a little current even if the secondary is open, conducting no current.

If you apply suitable AC to the primary, and a load to the secondary, current will flow in secondary and the current in the primary windings will increase.

Now...... A certain magnetic flux will exist in the core when the secondary has NO load.

THE QUESTIONS:

1) When the transformer is operating at its full design load, is the magnetic flux in the core larger, smaller, or the same as when there is no load?

2) If the secondary is shorted, so that a very large current flows, is the flux in the core larger, smaller, or the same as when there is no load?

Evan
09-18-2010, 09:52 PM
Flux is always highest under no load conditions.

J Tiers
09-18-2010, 09:59 PM
This would probably be a good time to mention the matter of "show your work".....

Or at least to give your reasoning.

Evan
09-18-2010, 10:02 PM
No load, low current draw, high back emf requires maximum flux.

Should mention losses include hysteresis in the iron, eddy currents in the iron, possible conduction between laminations, distance between laminations occupied by insulating material and a few others.

Forrest Addy
09-19-2010, 07:43 AM
If the primary voltage and frequency are constant, the magnetic flux stays consant regardles of secondary load even dead short -that is, in a perdect transformer.

In the real world I suppose there are small differences in total flux as the losses change over the transformer's load cycle.

What do I win? Did I win?

OK that's theory according to the book in Mr Wagner's electronc shop class 1958. But if the core flux stays contant why does magnetostrictive core noise (hum) increase with load? I could never figure that out.

Here's another. Moving magnet/changing flux induces electron flow in a winding. So take a 0.010 feeler and go around the windings of an energized transformer and you will feel little or no buzzing drag as you would from an AC magnet. I can see how air core transformers works but a closed iron core transformer abolutely stumps me. And yes I know an iron core increases coupling between AC wndings by a factor of everal hundred or more.

How does the linkage between iron core windings actually work so it explains the feeler behavior? Yeah, I know it works. I've been teaching and trouble-shooting transformers off and on for 50 years, even the water in pipes analogy, but once in a while somebody hands me this same poser and I have to fall back on "Well, it works.".Makes me feel dumb.

jdunmyer
09-19-2010, 11:25 AM
One thing I find interesting is that the parasitic current (probably not the correct term, but...) in the primary winding that appears during a no-load condtion seems to mostly disappear when the secondary is loaded.

I had a 240 -> 120 transformer, about 3 Kva in size that drew about 1/2 amp with no secondary load. Loading the secondary to 10 amps would give me just 5 amps on the primary, the 1/2 amp draw seemed to "disappear".

Duffy
09-19-2010, 11:49 AM
When I worked for the "Guvamint," we had office towers with as many as four 5 Mva transformers. At low load conditions, only one was supplying power and the others were on "standby." We determined that the three idle transformers were drawing 50 kw each just sitting there and we had a demand charge of $10.00/kw, plus our usage charge. I could not convince ANYBODY to al least turn off two of the four. The building I am referring to NEVER used more than one transformer, and only on the hottest days did the cooling fans on that unit come on for a few hours late in the day. Go figure!

Paul Alciatore
09-19-2010, 12:48 PM
If the primary voltage and frequency are constant, the magnetic flux stays consant regardles of secondary load even dead short -that is, in a perdect transformer.

In the real world I suppose there are small differences in total flux as the losses change over the transformer's load cycle.

What do I win? Did I win?

OK that's theory according to the book in Mr Wagner's electronc shop class 1958. But if the core flux stays contant why does magnetostrictive core noise (hum) increase with load? I could never figure that out.

Here's another. Moving magnet/changing flux induces electron flow in a winding. So take a 0.010 feeler and go around the windings of an energized transformer and you will feel little or no buzzing drag as you would from an AC magnet. I can see how air core transformers works but a closed iron core transformer abolutely stumps me. And yes I know an iron core increases coupling between AC wndings by a factor of everal hundred or more.

How does the linkage between iron core windings actually work so it explains the feeler behavior? Yeah, I know it works. I've been teaching and trouble-shooting transformers off and on for 50 years, even the water in pipes analogy, but once in a while somebody hands me this same poser and I have to fall back on "Well, it works.".Makes me feel dumb.

Several points here.

First, the basic question. The magnetic flux in the core is solely dependent on the net (vector) sum of the currents in the windings. The current in the primary is the first contributor. This current is at a mimimum when there is no load so the flux from this component is lower. As the load current increases, this primary current increases and the flux due to it also increases.

But there is also the current in the secondary and it also has an effect on the same flux that is creating it. Here you must also consider the fact that the secondary current is going to be 90 degrees out of phase with the primary. This is because it is created by the RATE OF CHANGE in the primary's flux, not the magnitude of the flux itself. This rate of change is greatest when the primary's current is actually zero (the current is sinusoidal and it's rate of change is greatest when the current is crossing the zero axis and hence is at a zero value). So the secondary current has to be added to the primaryís current using vectors. The resultant is going to be another sinusoidal function with a phase angle somewhere between the two contributors. In magnitude it will be close to the magnitude of the current in the primary alone and the actual relationship may depend more on the losses and secondary effects than on the actual primary and secondary currents. In total, the overall flux will be at a minimum when there is no load and it will increase as the load increases. This relationship will be more or less linear.

Second, the hum increases with load. Yes, this does happen. The transformers are constructed to contain the flux inside the cores. Any flux that in not contained is wasted as EM radiation (radio waves) so an efficient transformer contains all the flux. In reality, this is not perfect and some does escape. A big contributor to this escaped flux, escaped EM radiation, is the wire leads going into and out of the transformer. They are not actually part of the windings so the magnetic (EM) field around them CAN and DOES escape more easily. This is a principal contributor to the hum you typically hear around high power transformers. You will also hear it around switchgear. The steel cabinet can pick up the radiated EM field and vibrate (hum). This can happen even if there are no magnetic breakers in the cabinet. Same idea: itís the wires themselves that radiate. Also, the core of the transforner itself can contribute to hum. If the laminations are not completely impregnated with the varnish to fix them, they can move and hence, hum. You will also hear it near high Voltage lines even with no transformers in the vicinity. The wires themselves can vibrate from their mutual fields.

Finally, your feeler. An AC magnet is designed to have an external magnetic field. That is itís purpose. This field is not only present at the poles, but in the space between the poles and in general it is present to some degree all around the magnet. So I would totally expect a probe or feeler to detect it. On the other hand, a transformer is designed to contain as much of the field/flux as possible. So, much less would be present in the space around it and it would be harder to detect. A more sensitive instrument would probably find some.

Paul Alciatore
09-19-2010, 12:53 PM
No load, low current draw, high back emf requires maximum flux.

Should mention losses include hysteresis in the iron, eddy currents in the iron, possible conduction between laminations, distance between laminations occupied by insulating material and a few others.


The high back EMF does not require a maximum flux because there is little or no current flowing. It is not the magnitude of the flux that produces the EMF in the secondary, it is the RATE OF CHANGE of that flux that is proportional to the EMF produced. With no load to load down the EMF in the secondary, it can go quite high with a relatively low level of flux.

squirrel
09-19-2010, 01:07 PM
I thought Faraday and Lentz already solved this problem...

Evan
09-19-2010, 01:15 PM
The flux is always highest at no load for the reasons I have given.

jugs
09-19-2010, 06:46 PM
One thing I find interesting is that the parasitic current (probably not the correct term, but...) in the primary winding that appears during a no-load condtion seems to mostly disappear when the secondary is loaded.

I had a 240 -> 120 transformer, about 3 Kva in size that drew about 1/2 amp with no secondary load. Loading the secondary to 10 amps would give me just 5 amps on the primary, the 1/2 amp draw seemed to "disappear".

If a current flows in the primary, the magnetic field is still exciting the molecules in the core & secondary & producing a secondary potential even if no secondary load, so it is doing 'work' seen as heat

john
:)

whitis
09-19-2010, 08:30 PM
Transformers - The Basics (Section 1)
http://sound.westhost.com/xfmr.htm'
Part 2 actually deals with when the flux is higher

darryl
09-19-2010, 08:50 PM
If there is no load on the secondary, the primary winding resistance plus the core losses are what's responsible for producing the heat. Yes, there will be the full level of transformed voltage present on the secondary, and the losses incurred by the secondary are purely due to the winding resistance, and only when current flows in it. When the secondary is loaded, both windings will produce heat through losses.

Here's a question for those more knowledgeable that I on the subject- To start with, you have a magnetizing current in the core, and it can reach the saturation point of the iron. At the point this occurs, the inductance drops and the primary current increases, causing the winding to heat more. If you load the secondary, does this get you away from the saturation point to any extent? If what Evan is saying is true, and I believe it is, then by having some steady load on the secondary, you should be able to get away with a few less turns on the primary without driving the core into saturation. Of course the reverse should also be true- if you then unloaded the secondary completely, the core should be driven closer to saturation, maybe too close- does any of this make sense?

macona
09-19-2010, 09:19 PM
I cant answer the question until I know if the transformer in question is an Autobot or a Decepticon.

Evan
09-19-2010, 09:36 PM
if you then unloaded the secondary completely, the core should be driven closer to saturation...

Exactly. That is how a voltage regulating saturating core transformer works. It wouldn't be of much use if it only down "regulated" in proportion to increasing load. Ordinary transformers do that just fine. :rolleyes:

J Tiers
09-19-2010, 09:41 PM
The flux is always highest at no load for the reasons I have given.

Actually, so far you have not really GIVEN any "reasons", so your answer, right or wrong, won't be scored very high......

BTW, the answer and reasoning is VERY SIMPLE, and is almost in the category of "slap ya head" when you realize it.

Evan
09-19-2010, 10:19 PM
You are just pouting because I answered the question only 4 minutes after you posted it which means I didn't even have time to look it up. I didn't need to.

arcs_n_sparks
09-19-2010, 10:24 PM
This seems to be catching up on the "falling water" thread, with all the same attributes. :cool:

J Tiers
09-19-2010, 10:42 PM
You are just pouting because I answered the question only 4 minutes after you posted it which means I didn't even have time to look it up. I didn't need to.

I expected you to post first.... you have said your read cycle is 30 min to an hour....

But I am asking that all answers include an intelligible reason (right or wrong)........... I don't care if you post a right or wrong answer, so long as there is a chain of reasoning given with it.

An answer with no reasoning is scored as a "guess". I expect more from folks who ought to know more.

Evan
09-19-2010, 11:19 PM
See, I was right.

PeteF
09-20-2010, 12:28 AM
You are just pouting because I answered the question only 4 minutes after you posted it which means I didn't even have time to look it up. I didn't need to.

Oh dear :rolleyes:

boslab
09-20-2010, 01:02 AM
Its fairly rare to make transformer lams out of pure iron,most i've seen this last 20 odd years have been made from Silicon steel, quite low or even ultra low carbon as the leccy wizzards like it that way because of aforementioned problems like perrmisivity, noise, heat etc.
we call the stuff Grain Orintated or G.O., it normally has about 1.6% Si up to 3% and trials for higher and as a cosequence has to be 'Hot Connected', Blast furnace iron, Basic Oxygen Steelmaking For an oxy blow to make iron/scrap into steel [Unfortunatly the first thing that gets blown out is the Si, followed by the Carbon, the Si. reduction is exothermic so temp rises rapidly from 900-1000 up to 1600 to 1800 in about 3 mins, for a 350 ton converter full]
Then you have to put the Si back in at secodary steelmaking, its difficult as it either wont mix, burns off or floats on the top so making a ladle full takes ages, the maximum nomber most plants can manage is about 3 in close succesion.
after that struggle it goes to a continuous caster and gets turned into slab of the appropriate with and length [say 1000 x 234 x 9000 depending on the rehear furnace on the mill]
Whilst its still glowing red it gets whipped to the hot rolling mill, reheated to rolling temp 800-950 no more as it slumps in the furnace and hot reduced to 25 mm, then immidiatly through a 7 stand rolling mill down to finished gauge.
You cannot reheat a Silicon slab once cold as if left to its own devices the crystalisation within the slab produces the biggest crystals in steelmaking, 6" accros the face is common, this causes the slab to rupture like toughend glass, ive heared a slab cooling and the noise describes the process quite well, they call it [came from Bethlehem] chink cracking.
thats why the steel has to be kept hot or hot connected.
the magnetic properties are as you have all pointed out but i thought you might like to know a bit about making the stuff as most of the worlds not interested!
sorry for the long winded post
http://www.corusgroup.com/en/products/electrical_steels/electrical_steels_general/
http://www.orb.gb.com/unisil/guaranteed-magnetic-properties/
all the best
mark

darryl
09-20-2010, 02:09 AM
Mark, you have raised a question regarding electrical steel. If grain oriented, it's probably only going to be used for toroids or C cores, where the direction of the magnetic flux is always in the grain direction. Typical E core transformers wouldn't be able to use it to advantage- or so it seems. I wonder at what point are the differences large enough or important enough to warrant the use of what probably is a more expensive steel? I'm imagining here that even the toroids I see in higher end audio amplifiers are probably wound with non-grain oriented steel for the cost savings. Then I think of audio output transformers- what kind of steel is going to be in those? And more aptly, what would be the ideal steel to use in an output xfmr? I'm thinking it should be that 'new' ribbon steel, the stuff that's cooled at a million degrees per second as it's sprayed onto a fast moving drum. Is that even available to a consumer?

The Artful Bodger
09-20-2010, 02:44 AM
And now for another question..

I have a transformer with three windings, 240V primary, secondary of 48V and a second secondary of 680V which was connected in series with a capacitor and nothing else.

I assume this third circuit stabilised the voltage somehow but what would be the effect of varying the value of that capacitor?

philbur
09-20-2010, 03:35 AM
Arn't you always.:rolleyes:

Phil:)


See, I was right.

Evan
09-20-2010, 03:39 AM
About Jerry? Usually. He needs to remember that if he goes fishing he needs to make sure he has the right tackle. Otherwise he may be the one that is caught.

J Tiers
09-20-2010, 10:11 PM
Well, we seem to have few takers here.....

As far as I can tell, of the posts, the ones who gave an answer are Evan and Forrest.

Darryl and Paul A I don't think actually gave an answer. The rest didn't, for sure. Whitis (who ought to know the correct answer and reasons) gave a reference, but no answer.

OK.

The right answer is that the heavier the load, the less the flux.

But the REASON was only hinted at by those who answered, although both Forrest and Evan could argue that their answers "include" the reason. But neither came out and said it, so they can't have "full credit".

The simple, head-slap reason is that wires have resistance. The more current that flows, the more voltage is dropped in the resistance.

So.... Under a heavier load, more voltage is dropped across the resistance, and so less voltage needs to be "held off" by the inductance. There is less voltage available to drive current through the primary (fewer "volt-seconds"), so less current, and thus less flux.

Therefore the magnetizing current is less, and so the flux level is less as the load increases.. A short circuit being a very heavy load, it drops more voltage in resistance than rated load.

An ideal transformer would not HAVE any "magnetizing current". it would draw current only when a load was on the secondary. And the secondary current would perfectly cancel the flux of the primary current.

As for the hum that increases with load....... All actual physical transformers have "leakage inductance". This is essentially due to flux which is NOT canceled by the secondary current. it is not "cutting" both coils, and does not pass through the core in the normal way.

It may PARTLY pass through the core, but completes its linkage to one or the other coil through air. The flux from this "leakage field" , since it is NOT linked to or canceled by that due to secondary current, increases with current. If anything is loose, this increasing field can cause it to vibrate and make audible hum.

Evan
09-20-2010, 11:06 PM
As for the hum that increases with load....... All actual physical transformers have "leakage inductance". This is essentially due to flux which is NOT canceled by the secondary current. it is not "cutting" both coils, and does not pass through the core in the normal way.

It may PARTLY pass through the core, but completes its linkage to one or the other coil through air. The flux from this "leakage field" , since it is NOT linked to or canceled by that due to secondary current, increases with current. If anything is loose, this increasing field can cause it to vibrate and make audible hum.

You only get partial credit for that entire answer since that quoted part is incorrect. The primary cause of hum from a transformer is an effect called magnetostriction. The iron laminations actually change their shape as the flux intensity alternates along with the AC current that energises the core. While loose components may contribute to this even a transformer with absolutely no loose parts will still hum due to magnetostriction.

J Tiers
09-20-2010, 11:32 PM
You only get partial credit for that entire answer since that quoted part is incorrect. The primary cause of hum from a transformer is an effect called magnetostriction. The iron laminations actually change their shape as the flux intensity alternates along with the AC current that energises the core. While loose components may contribute to this even a transformer with absolutely no loose parts will still hum due to magnetostriction.

Ah.... of course the increasing flux is what does it... and that is due to leakage, since the main flux decreases.

Magnetostriction is not that strong on most transformer iron either.

But I have no problem with part credit........ This was not a physics PHD defense with a "why is the sky blue" question...... :D

Forrest Addy
09-20-2010, 11:45 PM
I suppose I could whine and weasel and thereby better my standing in this non-contest but my electrical smarts are scant so I will content with myself with a well-earned "almost"

Evan
09-20-2010, 11:55 PM
Time to do the Google tango.



In practice, the noise output of a transformer core is due mainly to magnetostriction. Compressive stresses in core sheets need to be avoided. The importance of sheet flatness is emphasized, and well oriented material is desirable. Two laboratory methods of producing a low-magnetostriction material are discussed.

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5323444




Transformer noise is caused by a phenomenon called magnetostriction. In very simple terms this means that if a piece of magnetic sheet steel is magnetized it will extend itself. When the magnetization is taken away. I goes back to its original condition. A transformer is magnetically excited by an alternating voltage and current so that it becomes extended and contracted twice during a full cycle of magnetization.
http://www.federalpacific.com/university/transnoise/chapter2.html

A.K. Boomer
09-21-2010, 07:04 AM
I opened this thread saying to myself here we go - what are you doing in a thread about EE and why in the world would you be in one that's being called an EE brain teaser,

but the OP is about as elementary as it gets and Evan hit the nail on the head right off the batt while others (i won't mention any names) got it drastically wrong,
A simple auto ignition coil is basically a transformer, Flux in the core is the transference work horse that gets the job done, its induced by the primary coil and is transferred over to the secondary by means of fluctuation the core material.

If there is no load on the secondary then there is no place for the work horse to transfer its energies - so it swings wildly fore and aft or "alternates"

If the secondary is shorted then it gets to reap most of this fluctuating energy from the core much in the same way the energies were instilled in the core by the primary.

What im surprised about is that JT is the one who started this topic,

and equally surprised it actually got heavily debated at first...:rolleyes:

J Tiers
09-21-2010, 08:46 AM
but the OP is about as elementary as it gets and Evan hit the nail on the head right off the batt while others (i won't mention any names) got it drastically wrong,
A simple auto ignition coil is basically a transformer, Flux in the core is the transference work horse that gets the job done, its induced by the primary coil and is transferred over to the secondary by means of fluctuation the core material.

If there is no load on the secondary then there is no place for the work horse to transfer its energies - so it swings wildly fore and aft or "alternates"

If the secondary is shorted then it gets to reap most of this fluctuating energy from the core much in the same way the energies were instilled in the core by the primary.



OOOOOOOOOOOOOOOOOOOkAAAAAAAAAAAAAAAAYYYYYYYY...... ..:eek:

A.K. Boomer
09-21-2010, 10:25 AM
Hey don't blame me JT, your the one that asked the "brain teaser" question:rolleyes:


What did you think happens? no change with the flux regardless of what the secondary does? Yippy - put as much load on it as you can and we will get "free energy" can't wait to build my perpetual motion machine!!!

hey -- how come my electric bills so high when I use more - I mean all there is is a transformer on my telephone pole that's always working - what does it matter what im milking off the secondary if JT says its "OK":rolleyes:

Come on JT, your better than this...


Letter from the electrical company; Dear valued customer, It has been brought our attention by a prodigy of a man named JT that the magnetic flux in our transformer cores does not change regardless of what kind of resistance the secondary coils are experiencing - This has changed everything that weve ever known about electricity - what this means to you is that you can use whatever power you want and will only be charged a minimum flat rate for power line maintenance and also since there is no longer a need for meter reading this will provide further savings, Furthermore, We have figured out a way to re-route some of the secondary energies back into the primary coils so we have also eliminated the need for power plants as these will be continually regenerating systems,
There will be compensation checks for years to come that will most likely be larger than what your future electric bills will be -- we apologize for any inconvenience this may have caused, God bless --- sincerely, Your electric company...

arcs_n_sparks
09-21-2010, 09:27 PM
Surprised no one mentioned ampere-turns. That explains why there is no free energy.........Sorry.......

J Tiers
09-21-2010, 09:29 PM
Hey don't blame me JT, your the one that asked the "brain teaser" question:rolleyes:


What did you think happens? no change with the flux regardless of what the secondary does? Yippy - put as much load on it as you can and we will get "free energy" can't wait to build my perpetual motion machine!!!

hey -- how come my electric bills so high when I use more - I mean all there is is a transformer on my telephone pole that's always working - what does it matter what im milking off the secondary if JT says its "OK":rolleyes:

Come on JT, your better than this...




Um..... the flux in the core DOES change under load............ did you forget to read first and type later? It DECREASES.

That's the interesting part.... the reason, which is why it's a "brainteaser"...... very few folks, EVEN EEs, will come up with the right reason WHY it changes, and HOW it changes, unless they happen to design transformers. I don't now, but I have designed them, so......

I have had people argue that it INCREASES, or that it stays the same, all with good reasons....

It's a little counterintuitive that it DECREASES........but it does. You seem to have missed that point when it was made prior to your rant......... Nothing against you, but you ain't exactly lookin real schmart here.....

A.K. Boomer
09-21-2010, 09:58 PM
JT -- I would think by me saying;
"What did you think happens? no change with the flux regardless of what the secondary does?"

Would mean to you that the;
"flux in the core DOES change under load" like you just stated and finally answered your original question.


Its not counter intuitive that it decreases, not at all - it makes perfect sense and follows all the typical laws of energy physics - I would love to here one of your EE friends argue that it actually increases or stays the same and like you say "all with good reason"

Its of course not going to stay the same or get bigger - like I stated - if it did then we can all tell the middle east to shove it... Comprendo?

Nothing against you either - Like I stated this OP is polar opposite to your usual track record (compliment);)

Henro
09-21-2010, 10:04 PM
[QUOTE= Nothing against you, but you ain't exactly lookin real schmart here.....[/QUOTE]

OK...Nothing against me either....But...What's this got to do with HSM???

I suggest you take this thread and shove it up some EE forum...

Along with your attitude...

J Tiers
09-21-2010, 11:42 PM
AK, the folks who argued for an increase, were using increased current as a reason..... And used the other argument too, about a phase shift and consequent non-cancellation of currents. all kinds of "good" reasons.

I've actually seen the "short circuits push it to saturation" argument right here on the forum......

I figured we'd see some of that here.... Oh well..... no fun today.

Anyway, it's not that important..... But then didn't we have a few pages on whether an airplane can take off if it's on a conveyor belt instead of a runway? Maybe that was PM, dunno.

Wasn't that important either, but it shore got folks het up, busy, and posting. All good clean fun, no bar fights (well maybe a few.... we could get Evan, Airsmith, and now Henro going, maybe)

boslab
09-22-2010, 09:14 PM
Mark, you have raised a question regarding electrical steel. If grain oriented, it's probably only going to be used for toroids or C cores, where the direction of the magnetic flux is always in the grain direction. Typical E core transformers wouldn't be able to use it to advantage- or so it seems. I wonder at what point are the differences large enough or important enough to warrant the use of what probably is a more expensive steel? I'm imagining here that even the toroids I see in higher end audio amplifiers are probably wound with non-grain oriented steel for the cost savings. Then I think of audio output transformers- what kind of steel is going to be in those? And more aptly, what would be the ideal steel to use in an output xfmr? I'm thinking it should be that 'new' ribbon steel, the stuff that's cooled at a million degrees per second as it's sprayed onto a fast moving drum. Is that even available to a consumer?
Im sorry, i cant really answer your question properly, whilst if i get an order for a specific chemistry steel i can usually make it and get kicked up the arse when i dont as a miscast of hisil or lowsil can cost £250,000 as there are no other applications you can use the stuff for really, other than scrap metal.
the punching line are tight on geometry and punch at all sorts of crazy angles relative to strip direction and to be honest i dont really get a lot of the magnetic theory as thier reasearch department is inhabited by magnetic fanatics who live, eat and breathe theory i dont understand at all!,
I normally get the pleasure of making the stuff they request, or at least analysing it to make sure its within specification.
Myself i have to admit i have a fascination with magnets! but even after long teatime debates with guys with Phd in magnetic properties of steel, they tell me what it does, why it does it, prove it mathematically, argue a lot and drink my tea.
none of them have ever been able to tell me to my satisfaction, what magnetism is. [liquid steel is not magnetic at all once it passes the Curie point]
Im not going to say i know a lot about the metal spray ribbon other than SSAB and Sandvic seem to be playing with it as thier budget for that area of reasearch is fairly big, and i'm sure it will lead to another type of magnetic core lamination with an equally bizzare brand name and a pile of patents!
regards
mark

Arcane
09-22-2010, 11:14 PM
hey -- how come my electric bills so high when I use more - I mean all there is is a transformer on my telephone pole that's always working - what does it matter what im milking off the secondary if JT says its "OK":rolleyes:



Just for clarification and accuracy, that would be an electrical utility pole...or as is it is more commonly called...a power pole. Electrical utilities own any pole that has power lines and equipment on them and rent dedicated defined space on them for telecommunication circuits.